Baoshan Paint Office Chair Repair

The repair of painted office chairs in Baoshan District needs to be carried out in a targeted manner according to the type of damage, with core steps including surface coating repair, connection structure reinforcement, and environmental adaptation.

1. Surface Coating Failure Treatment

Acidic gases such as sulfur dioxide and nitrogen oxides in the air of Baoshan District can accelerate the breakage of the resin cross-linking structure in the paint film of office chairs, leading to paint film peeling or blistering. The salt in hand sweat seeps into the micropores of the paint film, and due to the osmotic pressure difference caused by the day-night temperature difference, it further triggers local blistering. When repairing, do not directly apply new paint. First, sand the surface with sandpaper until the base material is exposed, remove the weak layer of the old paint film, and then use diluted sealing primer to block the capillary channels to prevent the new paint layer from peeling off again.
The repair methods vary depending on the type of coating:

• Nitrocellulose lacquer: It can achieve interlayer fusion through solvent dissolution, using the chemical compatibility between the original coating and the new paint to enhance adhesion.
• Polyurethane paint: It relies on intermolecular forces to fill defects. It is necessary to ensure that the surface of the base material is clean and dry to avoid the influence of solvent residues on the curing effect.

2. Connection Structure Failure Repair

During long-term use of office chairs, the mortise-and-tenon or screw connections between the chair legs and cross-braces can experience stress concentration due to vertical pressure and horizontal shear force, resulting in micrometer-scale plastic deformation of the wood fibers or metal thread contact surfaces and an increase in the connection gap. The relatively high humidity in Baoshan District causes wood to absorb moisture and expand and then shrink when drying, which accelerates this process. The repair needs to restore the preload at the connection.

• Mortise-and-tenon structure: Fill the gap with wooden wedges to increase the frictional force on the contact surface and prevent loosening.
• Screw connection: Replace with self-locking nuts to avoid secondary loosening caused by simply tightening the screws.
  If torsional fatigue occurs due to asymmetric forces (such as damage to a single armrest), it is necessary to implant wood fiber-reinforced resin (a mixture of woodworking glue and fine wood shavings) into the damaged hole. After curing, re-drill the hole to restore the thread bite strength. At the same time, check the undamaged nodes on the opposite side to prevent stress redistribution from causing secondary damage.

3. Repair Decision-Making and Process Selection

Repairs should be carried out in a graded manner according to the type and degree of damage:

• Minor scratches (depth < 0.1 mm): Use micro-grinding technology for polishing to avoid damaging the base material.
• Structural fractures (such as fractures in the legs of tables and chairs): Analyze the texture direction of the fracture surface. If it has repair value, choose a filling material with a density matching that of the original material (such as epoxy resin). Note that the curing time is inversely proportional to the ambient temperature, and the construction ambient temperature needs to be controlled to ensure the curing effect.

4. Environmental Factor Consideration

The annual average humidity change in Baoshan District affects the curing process of repair materials. After repair, the furniture should be left to stand in an environment with a humidity of 45%-55% for 7-10 days to allow the materials to fully cure and reach a stable state, avoiding deformation or paint film cracking due to humidity fluctuations.